N-myc downstream-regulated gene 1 downregulates cell proliferation, invasiveness, and tumorigenesis in human oral squamous cell carcinoma

Blocking β2-AR and Inhibiting COX-2: A Promising Approach to Suppress OSCC Development

OBJECTIVES

β2-adrenergic receptor (β2-AR) and cyclooxygenase-2 (COX-2) are overexpressed in various malignant tumours including oral squamous cell carcinoma (OSCC), suggesting that they may contribute to the development of OSCC. This study aims to investigate the potential synergistic effect of β2-AR blockade and COX-2 inhibition on suppressing the development of OSCC.

METHODS

Effects of blocking β2-AR and inhibiting COX-2 on migration and invasion of OSCC cells were detected by wound-healing assay and transwell invasion assay. Western blot and enzyme-linked immunosorbent assay (ELISA) were used to detect the expression of genes related to the progression of OSCC. In vivo, OSCC xenograft models were established to evaluate the effect of combined treatment on survival time, tumour size, and submandibular lymph node metastasis. Immunohistochemistry, Western blot, and ELISA were used to detect the expression of invasion and metastasis relative genes.

RESULTS

In vitro, blocking β2-AR or inhibiting COX-2 alone could suppress invasion and metastasis of OSCC cells, and suppression with combined treatment was more significant. Expression of genes related to invasion and metastasis, including EGFR, TGF-β1, IL-1β, MMP2, and VEGFA, were downregulated significantly, especially in the combined treatment group. In vivo, the combined treatment could significantly prolong survival time in tumour-bearing mice and inhibit the growth of tumours. Furthermore, submandibular lymph node metastasis was less in the combined treatment group, and expression of the abovementioned genes was also downregulated.

CONCLUSIONS

The combination of β2-AR blockade and COX-2 inhibition can significantly suppress the development of OSCC via downregulating EGFR, TGF-β1, IL-1β, MMP2, and VEGFA. Findings suggest that the combined use of a β2-AR blocker and a COX-2 inhibitor could be a promising adjuvant therapy in OSCC. Both drugs are commonly prescribed, and their safety and efficacy are well established. Their use in adjuvants in OSCC should therefore be promoted in clinical practice.

ETS1 regulates NDRG1 to promote the proliferation, migration, and invasion of OSCC

OBJECTIVE

The aim of this study was to investigate the molecular mechanism by which the transcription factor ETS1 regulates N-myc downstream regulatory gene 1 (NDRG1) to provide a new theoretical basis for the study of oral squamous cell carcinoma (OSCC).

METHODS

In this study, eight human OSCC and paraneoplastic samples were collected. The expressions of NDRG1, ETS1, and Ki67 were detected by immunohistochemistry; apoptosis was detected by tdt-mediated dUTP notched end labeling; cell migration and invasion were detected by Transwell; quantitative real-time PCR was performed to detect the expression of NDRG1; RNA-binding protein immunoprecipitation (RIP) assays detected NDRG1 expression; immunofluorescence assays detected ETS1 expression.

RESULTS

NDRG1 and ETS1 expression was significantly upregulated in cancer tissues and CAL-27 and SCC-6 cells. Knockdown of NDRG1 and ETS1 inhibited cell proliferation, migration, invasion, cloning, and EMT while promoting apoptosis and inhibited tumor development; ETS1 positively regulated NDRG1 expression; Finally, overexpression of NDRG1 in vivo and in vitro reversed the effect of ETS1 knockdown on CAL-27 and SCC-6 cells.

CONCLUSIONS

ETS1 positively regulates the expression of NDRG1 and promotes OSCC. Therefore, ETS1 may serve as a new target for the clinical diagnosis and treatment of OSCC.

DYNLT3 overexpression induces apoptosis and inhibits cell growth and migration via inhibition of the Wnt pathway and EMT in cervical cancer

The role of the dynein light chain Tctex-type 3 (DYNLT3) protein in the biological behavior of cervical cancer and its relative molecular mechanisms were investigated. Immunohistochemical staining was used to detect DYNLT3 protein expression in cervical cancer tissues. Cell proliferation and apoptosis rates and invasiveness and migratory capacities were determined by CCK-8 assays, BrdU staining assays and colony formation assays, fluorescence activated cell sorting (FACS), wound healing assays, and Transwell invasion assays of cervical cancer cells after DYNLT3 modulation. The expression levels of Wnt signaling pathway- and EMT-related proteins were examined by Western blotting. Furthermore, the effects of DYNLT3 on the tumorigenicity and metastasis of cervical cancer in nude mice were analyzed by performing immunohistochemistry, and we found that the expression level of the DYNLT3 protein was higher in human normal cervical tissues than in cervical cancer tissues. Overexpression of DYNLT3 obviously attenuated the proliferation, migration and invasion of CaSki and SiHa cells, and promoted cell apoptosis. Upregulation of DYNLT3 expression markedly decreased the expression of Wnt signaling pathway-related proteins (Dvl2, Dvl3, p-LRP6, Wnt3a, Wnt5a/b, Naked1, Naked2, β-catenin and C-Myc) and EMT-related proteins (N-cadherin, SOX2, OCT4, vimentin and Snail), and increased the expression of E-cadherin and Axin1. However, the opposite results were observed after down-regulation of DYNLT3 expression. Up-regulation of DYNLT3 expression significantly inhibited tumor growth in a nude mouse model, while downregulation of DYNLT3 showed the opposite results. In addition, the major metastatic site of cervical cancer cells in mice was the lung, and downregulation of DYNLT3 expression increased cancer metastasis in vivo. DYNLT3 exerted inhibitory effects on cervical cancer by inhibiting cell proliferation, migration and invasion, promoting cell apoptosis in vitro, and inhibiting tumor growth and metastasis in vivo, possibly by suppressing the Wnt signaling pathway and the EMT.

MiR-96-5p induced NDRG1 deficiency promotes prostate cancer migration and invasion through regulating the NF-κB signaling pathway

OBJECTIVE: The N-myc downstream-regulated gene 1 (NDRG1) has been discovered as a significant gene in the progression of cancers. However, the regulatory mechanism of NDRG1 remained obscure in prostate cancer (PCa). METHODS: The miR-96-5p and NDRG1 expression levels were evaluated in PCa cell lines, prostate tissues, and validated public databases by real-time PCR, western blot analysis, and immunohistochemistry. The function of miR-96-5p and NDRG1 were investigated by wound healing and transwell assays in vitro, and mouse xenograft assay in vivo. The candidate pathway regulated by NDRG1 was conducted by the next-generation gene sequencing technique. Immunofluorescence and luciferase assay was used to detect the relation between miR-96-5p, NDRG1, and NF-kB pathway. RESULTS: Overexpressing NDRG1 suppresses the migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro, and inhibits metastasis in vivo. Moreover, miR-96-5p contributes to NDRG1 deficiency and promotes PCa cell migration and invasion. Furthermore, NDRG1 loss activates the NF-KB pathway, which stimulates p65 and IKBa phosphorylation and induces EMT in PCa. CONCLUSIONS: MiR-96-5p promotes the migration and invasion of PCa by targeting NDRG1 and regulating the NF-κB pathway.

Multifaceted and Intricate Oncogenic Mechanisms of NDRG1 in Head and Neck Cancer Depend on Its C-Terminal 3R-Motif

N-Myc downstream-regulated 1 (NDRG1) has inconsistent oncogenic functions in various cancers. We surveyed and characterized the role of NDRG1 in head and neck cancer (HNC). Cellular methods included spheroid cell formation, clonogenic survival, cell viability, and Matrigel invasion assays. Molecular techniques included transcriptomic profiling, RT-qPCR, immunoblotting, in vitro phosphorylation, immunofluorescent staining, and confocal microscopy. Prognostic significance was assessed by Kaplan–Meier analysis. NDRG1 participated in diverse oncogenic functions in HNC cells, mainly stress response and cell motility. Notably, NDRG1 contributed to spheroid cell growth, radio-chemoresistance, and upregulation of stemness-related markers (CD44 and Twist1). NDRG1 facilitated cell migration and invasion, and was associated with modulation of the extracellular matrix molecules (fibronectin, vimentin). Characterizing the 3R-motif in NDRG1 revealed its mechanism in the differential regulation of the phenotypes. The 3R-motif displayed minimal effect on cancer stemness but was crucial for cell motility. Phosphorylating the motif by GSK3b at serine residues led to its nuclear translocation to promote motility. Clinical analyses supported the oncogenic function of NDRG1, which was overexpressed in HNC and associated with poor prognosis. The data elucidate the multifaceted and intricate mechanisms of NDRG1 in HNC. NDRG1 may be a prognostic indicator or therapeutic target for refractory HNC.

The role of N-cadherin/c-Jun/NDRG1 axis in the progression of prostate cancer

The dysregulation of androgen receptor (AR) signaling is a critical event in the progression of prostate cancer (PCa) and hormone therapy consisting of androgen deprivation (ADT) or AR inhibition is therefore used to treat advanced cases. It is known that N-cadherin becomes upregulated following ADT and can directly induce PCa transformation to the castration-resistant stage (CRPC). However, the relationship between AR and N-cadherin is unclear and may promote better understanding of CRPC pathogenesis and progression. Here, we demonstrate a new axis of N-cadherin/c-Jun/N-myc downstream regulated gene 1 (NDRG1) that N-cadherin promotes c-Jun expression and suppresses NDRG1 to promote invasion and migration of PCa cells through epithelial to mesenchymal transition (EMT). Targeting N-cadherin in combination with enzalutamide (ENZ) treatment synergistically suppressed PC3 cell proliferation in vivo and in vitro. Further studies showed that compared to lower Gleason score (GS) (GS < 7) cases, high GS (GS > 7) cases exhibited elevated N-cadherin expression and reduced NDRG1 expression, corroborating our in vitro observations. We further demonstrate that c-Jun, AR, and DNA methyltransferase-1 (DNMT1) form a complex in the 12-O-tetradecanoyl phorbol-13-acetate (TPA) response elements (TREs) region of the NDRG1 promoter, which suppresses NDRG1 transcription through DNA hypermethylation. In conclusion, we demonstrate an underlying mechanism for how N-cadherin collaborates with AR and NDRG1 to promote CRPC progression. Controlling N-cadherin/c-Jun/NDRG1 axis may help to overcome resistance to commonly used hormone therapy to improve long-term patient outcomes.

Caffeic acid and its derivatives as potential modulators of oncogenic molecular pathways: New hope in the fight against cancer

As a phenolic acid compound, caffeic acid (CA) can be isolated from different sources such as tea, wine and coffee. Caffeic acid phenethyl ester (CAPE) is naturally occurring derivative of CA isolated from propolis. This medicinal plant is well-known due to its significant therapeutic impact including its effectiveness as hepatoprotective, neuroprotective and anti-diabetic agent. Among them, anti-tumor activity of CA has attracted much attention, and this potential has been confirmed both in vitro and in vivo. CA can induce apoptosis in cancer cells via enhancing ROS levels and impairing mitochondrial function. Molecular pathways such as PI3K/Akt and AMPK with role in cancer progression, are affected by CA and its derivatives in cancer therapy. CA is advantageous in reducing aggressive behavior of tumors via suppressing metastasis by inhibiting epithelial-to-mesenchymal transition mechanism. Noteworthy, CA and CAPE can promote response of cancer cells to chemotherapy, and sensitize them to chemotherapy-mediated cell death. In order to improve capacity of CA and CAPE in cancer suppression, it has been co-administered with other anti-tumor compounds such as gallic acid and p-coumaric acid. Due to its poor bioavailability, nanocarriers have been developed for enhancing its ability in cancer suppression. These issues have been discussed in the present review with a focus on molecular pathways to pave the way for rapid translation of CA for clinical use.

Recent progresses in the pharmacological activities of caffeic acid phenethyl ester

The past decades have seen a growing interest in natural products. Caffeic acid phenethyl ester (CAPE), a flavonoid isolated from honeybee propolis, has shown multiple pharmacological potentials, including anti-cancer, anti-inflammatory, antioxidant, antibacterial, antifungal, and protective effects on nervous systems and multiple organs, since it was found as a potent nuclear factor κB (NF-κB) inhibitor. This review summarizes the advances in these beneficial effects of CAPE, as well as the underlying mechanisms, and proposes that CAPE offers an opportunity for developing therapeutics in multiple diseases. However, clinical trials on CAPE are necessary and encouraged to obtain certain clinically relevant conclusions.

NDRG1 regulates Filopodia-induced Colorectal Cancer invasiveness via modulating CDC42 activity

N-myc downstream regulated gene-1 (NDRG1) has been identified as a putative metastasis suppressor gene and proved to be a key player in cancer spreading and proliferation in our previous work. However, the effects of NDRG1 on tumor invasion and the mechanisms behind it are rarely understood. Here we provided in silico evidence that NDRG1 plays a crucial role in actin reorganization in colorectal cancer (CRC). Through in vitro experiments, we next observed filopodia formation was altered in NDRG1-modified cell lines, while cell division cycle-42 (CDC42) displayed excessive activation in NDRG1-silenced cells. Mechanistically, NDRG1 loss disrupts the binding between RhoGDIα and CDC42 and triggers the activation of CDC42 and the downstream cascades PAK1/Cofilin, thereby promotes the formation of filopodia and invasiveness of CRC. The knockdown of NDRG1 led to enhanced dissemination of CRC cells in vivo and correlates with active CDC42 expression. Using clinical sample analysis, we found an elevated level of active CDC42 in patients with advanced T stage, and it was negatively related to NDRG1 expression. In sum, these results uncover a mechanism utilized by NDRG1 to regulate CDC42 activity in coordinating cytoskeleton reorganization, which was crucial in cancer invasion.

Suppression of oral cancer by induction of cell cycle arrest and apoptosis using Juniperus communis extract

The oral cancer incidence rate is slowly increasing and is now the fifth leading cause of cancer-related death due to its high metastasis and recurrence rate. Juniperus communis is used as a traditional Chinese medicine and has been proven to have anti-cancer activity against neuroblastomas. In the present study, we further investigated the anti-cancer mechanisms of J. communis extract (JCo) on oral cancer and evaluated the synergistic effects of JCo combined with 5-fluorouracil (5-FU). We found that JCo inhibited oral cancer cell growth, and that JCo might be less cytotoxic to normal cells than to cancer cells. After JCo treatment, cell cycle arrest was observed at the G₀/G₁ phase through modulation of p53/p21 and Rb signaling. JCo also caused an increase in the sub-G₁ phase and cell apoptosis via the intrinsic and extrinsic apoptosis pathways. JCo combined with 5-FU presented a synergistic effect to reduce cell viability. In conclusion, JCo inhibited oral cancer cell growth by inducing cell cycle arrest and activating cell apoptosis, and JCo significantly synergized with 5-FU. JCo might have the potential to be an adjuvant and a new therapeutic drug for oral cancer treatment.

Expression of Claudin-1 in laryngeal squamous cell carcinomas (LSCCs) and its significance

BACKGROUND

A large body of scientific evidence points to the important roles of tight junction proteins in tumor development, progression and dissemination. The larynx has only a few studies, analyzing the role of this group of junctional proteins in its oncogenesis. In this study, the author sheds some light on the expression and possible role of claudin-1 in laryngeal squamous cell carcinomas.

MATERIALS AND METHODS

This study analyzed the expression of claudin-1, using immunohistochemistry, in a tissue microarray of 80 cases of laryngeal squamous cell cancers. Clinicopathological parameters were analyzed according to claudin-1 expression in the tissue microarray. Furthermore, the expression of slug/snail1, an Epithelial-Mesenchymal Transition (EMT) linked protein, was analyzed by immunohistochemistry in the same microarray, and the expressions of the two proteins were assessed for correlation.

RESULTS

A significant majority of laryngeal squamous cell cancers exhibited positive expression of claudin-1 proteins. The majority of those tumors expressed claudin-1 in their cytoplasm. The overall majority of those same tumors also exhibited a cytoplasmic shift of the slug-snail-1 protein from the nuclei to the cytoplasm. There was also evidence of correlation of the two proteins' expressions in the cytoplasm of laryngeal tumors.

CONCLUSION

The above may suggest a role for claudin-1 in the development and progression of laryngeal squamous cell carcinoma. Overall, claudin-1's aberrant expression in laryngeal cancer is in line with evidence seen in other head and neck cancers. Its co-expression with slug/snail-1 in LSCC patients should be investigated further to understand the nature of the relationship of the two proteins in LSCC and their possible contribution to its development and progression.

Reversing oncogenic transformation with iron chelation

Cancer cells accumulate iron to supplement their aberrant growth and metabolism. Depleting cells of iron by iron chelators has been shown to be selectively cytotoxic to cancer cells in vitro and in vivo. Iron chelators are effective at combating a range of cancers including those which are difficult to treat such as androgen insensitive prostate cancer and cancer stem cells. This review will evaluate the impact of iron chelation on cancer cell survival and the underlying mechanisms of action. A plethora of studies have shown iron chelators can reverse some of the major hallmarks and enabling characteristics of cancer. Iron chelators inhibit signalling pathways that drive proliferation, migration and metastasis as well as return tumour suppressive signalling. In addition to this, iron chelators stimulate apoptotic and ER stress signalling pathways inducing cell death even in cells lacking a functional p53 gene. Iron chelators can sensitise cancer cells to PARP inhibitors through mimicking BRCAness; a feature of cancers trademark genomic instability. Iron chelators target cancer cell metabolism, attenuating oxidative phosphorylation and glycolysis. Moreover, iron chelators may reverse the major characteristics of oncogenic transformation. Iron chelation therefore represent a promising selective mode of cancer therapy.

NDRG1 deficiency is associated with regional metastasis in oral cancer by inducing epithelial-mesenchymal transition

Regional metastasis is the single most important prognostic factor in oral squamous cell carcinoma (OSCC). Abnormal expression of N-myc downstream-regulated genes (NDRGs) has been identified to occur in several tumor types and to predict poor prognosis. In OSCC, the clinical significance of deregulated NDRG expression has not been fully established. In this study, NDRG1 relevance was assessed at gene and protein levels in 100 OSCC patients followed up by at least 10 years. Survival outcome was analyzed using a multivariable analysis. Tumor progression and metastasis was investigated in preclinical model using oral cancer cell lines (HSC3 and SCC25) treated with epidermal growth factor (EGF) and orthotopic mouse model of metastatic murine OSCC (AT84). We identified NDRG1 expression levels to be significantly lower in patients with metastatic tumors compared with patients with local disease only (P = 0.001). NDRG1 expression was associated with MMP-2, -9, -10 (P = 0.022, P = 0.002, P = 0.042, respectively) and BCL2 (P = 0.035). NDRG1 lower expression was able to predict recurrence and metastasis (log-rank test, P = 0.001). In multivariable analysis, the expression of NDRG1 was an independent prognostic factor (Cox regression, P = 0.013). In invasive OSCC cells, NDRG1 expression is diminished in response to EGF and this was associated with a potent induction of epithelial-mesenchymal transition phenotype. This result was further confirmed in an orthotopic OSCC mouse model. Together, this data support that NDRG1 downregulation is a potential predictor of metastasis and approaches aimed at NDRG1 signaling rescue can serve as potential therapeutic strategy to prevent oral cancer progression to metastasis.

Pharmacological targeting and the diverse functions of the metastasis suppressor, NDRG1, in cancer

N-myc downstream regulated gene-1 (NDRG1) is a potent metastasis suppressor that is regulated by hypoxia, metal ions including iron, the free radical nitric oxide (NO^.), and various stress stimuli. This intriguing molecule exhibits diverse functions in cancer, inhibiting epithelial-mesenchymal transition (EMT), cell migration and angiogenesis by modulation of a plethora of oncogenes via cellular signaling. Thus, pharmacological targeting of NDRG1 signaling in cancer is a promising therapeutic strategy. Of note, novel anti-tumor agents of the di-2-pyridylketone thiosemicarbazone series, which exert the "double punch" mechanism by binding metal ions to form redox-active complexes, have been demonstrated to markedly up-regulate NDRG1 expression in cancer cells. This review describes the mechanisms underlying NDRG1 modulation by the thiosemicarbazones and the diverse effects NDRG1 exerts in cancer. As a major induction mechanism, iron depletion appears critical, with NO^. also inducing NDRG1 through its ability to bind iron and generate dinitrosyl-dithiol iron complexes, which are then effluxed from cells. Apart from its potent anti-metastatic role, several studies have reported a pro-oncogenic role of NDRG1 in a number of cancer-types. Hence, it has been suggested that NDRG1 plays pleiotropic roles depending on the cancer-type. The molecular mechanism(s) underlying NDRG1 pleiotropy remain elusive, but are linked to differential regulation of WNT signaling and potentially differential interaction with the tumor suppressor, PTEN. This review discusses NDRG1 induction mechanisms by metal ions and NO^. and both the anti- and possible pro-oncogenic functions of NDRG1 in multiple cancer-types and compares the opposite effects this protein exerts on cancer progression.

Extract of Juniperus indica Bertol Synergizes with Cisplatin to Inhibit Oral Cancer Cell Growth via Repression of Cell Cycle Progression and Activation of the Caspase Cascade

Oral cancer—a type of head and neck cancer—is estimated to be the fifth most common cancer in Taiwan. However, efficacious therapies for oral cancer are still lacking due to drug resistance and recurrence. Consequently, the identification of new anticancer agents for clinical treatment is needed. Juniperus indica Bertol is a plant of the Juniperus genus often used as a treatment in traditional medicine due to its anti-inflammatory, antibacterial and diuretic functions. The biofunctions of Juniperus indica Bertol including its anticancer potential, have not been fully explored. As a result, the aim of this research was to investigate the anticancer activity of Juniperus indica Bertol extract (JIB extract) and determine whether JIB extract has synergistic effects with cisplatin in oral cancer. These results are the first to demonstrate that JIB extract exhibits anticancer capacity and synergizes with cisplatin to treat oral cancer. Our findings indicate that JIB extract has a potential to develop anticancer agent and chemo therapeutic adjuvant for oral cancer.

Donor Brain Death Leads to a Worse Ischemia-Reperfusion Injury and Biliary Injury After Liver Transplantation in Rats

BACKGROUND

Brain-dead (BD) donor is the main source for liver transplantation (LT). We aim to investigate the effect of brain death on donor liver inflammatory activity and its association with ischemia-reperfusion (I/R) injury and biliary tract injury after LT.

MATERIAL AND METHOD

A brain death model using male Lewis rats was established, in both BD and non-BD groups; livers were harvested for transplantation using a 2-cuff technique. The rats were sacrificed 12 hours (n = 10) or 4 weeks (n = 10) after transplantation. I/R injury and long-term biliary tract injury were observed after transplantation.

RESULTS

All rats survived for 4 weeks after transplantation. At 12 hours after BD-donor LT (BDDLT), liver injury worsened; serum transaminases, bilirubin, oxidative stress, inflammatory responses and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining level substantially increased (P < .05). At 4 weeks after BDDLT, serum bilirubin and bile lactate dehydrogenase and γ-glutamyl transpeptidase levels were elevated (P < .05). Biliary fibrosis and epithelial-mesenchymal transition (EMT) were detectable and NDRG1 gene expression was decreased.

CONCLUSIONS

These results suggested that brain death-induced inflammatory response in donor organs and resulted in a worse I/R injury and biliary tract injury after LT in rats. The brain death-related biliary tract injury may be associated with the regulation of EMT through NDRG1.

N-myc downstream-regulated gene 1 inhibits the proliferation of colorectal cancer through emulative antagonizing NEDD4-mediated ubiquitylation of p21

BACKGROUND

N-myc downstream-regulated gene 1 (NDRG1) has been shown to play a key role in tumor metastasis. Recent studies demonstrate that NDRG1 can suppress tumor growth and is related to tumor proliferation; however, the mechanisms underlying these effects remain obscure.

METHODS

Immunohistochemistry (IHC) was used to detect NDRG1 and p21 protein expression in colorectal cancer tissue, and clinical significance of NDRG1 was also analyzed. CCK-8 assay, colony formation assay, flow cytometry, and xenograft model were used to assess the effect of NDRG1 on tumor proliferation in vivo and in vitro. The mechanisms underlying the effect of NDRG1 were investigated using western blotting, immunofluorescence, immunoprecipitation, and ubiquitylation assay.

RESULTS

NDRG1 was down-regulated in CRC tissues and correlated with tumor size and patient survival. NDRG1 inhibited tumor proliferation through increasing p21 expression via suppressing p21 ubiquitylation. NDRG1 and p21 had a positive correlation both in vivo and in vitro. Mechanistically, E3 ligase NEDD4 could directly interact with and target p21 for degradation. Moreover, NDRG1 could emulatively antagonize NEDD4-mediated ubiquitylation of p21, increasing p21 expression and inhibit tumor proliferation.

CONCLUSION

Our study could fulfill potential mechanisms of the NDRG1 during tumorigenesis and metastasis, which may serve as a tumor suppressor and potential target for new therapies in human colorectal cancer.

Antioxidation and Antiapoptosis Characteristics of Heme Oxygenase-1 Enhance Tumorigenesis of Human Prostate Carcinoma Cells

Heme oxygenase-1 (HO-1) has antiinflammatory and antioxidant properties and is deemed as a tissue protector. However, effects of HO-1 in prostate cancer remain in controversy. We evaluated the role of HO-1 in prostate carcinoma in vitro and in vivo.

Overexpression of HO-1 did not affect prostate cell proliferation in the normal condition but enhanced cell proliferation under serum starvation. HO-1 overexpression enhanced cell invasion of PC-3 cells through epithelial–mesenchymal transition (EMT) induction, which was supported by increased Slug, N-cadherin, and vimentin expressions. In the xenograft animal study, HO-1 overexpression enhanced PC-3 cell tumor growth in vivo. HO-1 attenuated reactive oxygen species induced by H₂O₂ or pyocyanin treatment in PC-3 and DU145 cells. HO-1 further reduced PC-3 and DU145 cell apoptosis induced by H₂O₂ or serum starvation. Our results suggested that HO-1 was able to increase prostate carcinoma cell invasion in vitro and tumor growth in vivo. The EMT induction and antioxidant and antiapoptotic effects of HO-1 in the prostate carcinoma cells may be responsible for these findings.

TGFBI Promotes Tumor Growth and is Associated with Poor Prognosis in Oral Squamous Cell Carcinoma

Purpose: In a previous study, we found that transforming growth factor beta-induced (TGFBI) is a hub gene strongly associated with oral squamous cell carcinoma (OSCC), using gene chip meta-analysis and PPI network analysis. Thus, the present study was established to explore the role of TGFBI in the pathogenesis of OSCC and to define the underlying mechanisms.

Methods: The correlations between TGFBI expression and the clinicopathological features and prognosis of OSCC were analyzed. Then, TGFBI-knockout HSC-3 cell lines were constructed using the CRISPR/Cas9 system. Cell proliferation, migration, and invasion in vitro were determined by cell counting, CCK-8, colony formation, and Transwell assays. Moreover, a xenograft animal study was implemented to determine the tumorigenicity and metastatic ability associated with TGFBI in vivo. The genes and pathways differentially expressed after TGFBI knockout were determined using transcriptional sequencing and bioinformatics.

Results: TGFBI expression was significantly higher in OSCC than in normal tissue. Its high expression was also correlated with high stage and was predictive of poor prognosis, as we expected. Knockout of TGFBI inhibited cell proliferation and clone formation, and enhanced cell migration and invasion in vitro. Besides, the xenograft animal study showed that TGFBI knockout suppressed tumor growth and metastasis in vivo. Furthermore, transcriptome sequencing revealed that genes associated with cell proliferation, metastasis, and inflammatory responses exhibited a change of expression upon TGFBI knockout. GO and KEGG analyses indicated that the function of TGFBI is related to responses to bacteria and inflammatory responses.

Conclusions: TGFBI overexpression can promote OSCC and is associated with poor prognosis in OSCC patients. TGFBI knockout can inhibit cell proliferation and metastasis in vivo. TGFBI may alter cell responses to bacteria, which causes an imbalance in the immune inflammatory response and promotes the development of OSCC.

NDRG1 suppresses vasculogenic mimicry and tumor aggressiveness in gastric carcinoma

N-myc downstream regulated gene 1 (NDRG1) has been well characterized as a suppressor of metastasis in numerous types of carcinoma. NDRG1 inhibits the metastatic progression of cancer cells via its inhibitory effects on a wide variety of cellular signaling pathways. Vasculogenic mimicry (VM) refers to the unique ability of aggressive tumor cells to mimic the pattern of embryonic vasculogenic networks, and is the main reason for the poor prognosis and failure of antivascular therapy in gastric carcinoma (GC). Tumor cells can mimic the function of endothelial cells to exhibit VM through epithelial-mesenchymal transition (EMT). However, the potential function of NDRG1 in metastatic GC progression in patients has not yet been fully elucidated. To date, data regarding the function of NDRG1 in VM formation in GC have not been reported. The aim of the present study was to elucidate these unknown areas. To this end, 228 samples of human GC were used to identify the protein expression levels of NDRG1, VM-associated proteins and EMT-associated proteins via immunohistochemistry, and their clinical significance was assessed. In addition, the data of 415 patients with GC were collected from The Cancer Genome Atlas database. A functional enrichment analysis concerning NDRG1 was performed using Metascape and the Gene Set Enrichment Analysis (GSEA). In conclusion, the results of the present study indicate that NDRG1 is negatively correlated with poor prognosis through suppression of VM formation in GC. The results of the present study demonstrated that NDRG1 decreases EMT-associated protein expression and that HER2 expression may serve a significant role in this process. The Metascape and GSEA results also indirectly support this conclusion. The present study discusses the status NDRG1 as a prognostic and selective biomarker in GC, as well as current and future NDRG1-targeted therapies.

The enigmatic role of matrix metalloproteinases in epithelial-to-mesenchymal transition of oral squamous cell carcinoma: Implications and nutraceutical aspects

The most prevalent malignancy in the oral cavity is represented by oral squamous cell carcinoma, an aggressive disease mostly detected in low-income communities. This neoplasia is mostly diffused in older men particularly exposed to risk factors such as tobacco, alcohol, and a diet rich in fatty foods and poor in vegetables. In oral squamous cell carcinoma, a wide range of matrix-cleaving proteinases are involved in extracellular matrix remodeling of cancer microenvironment. In particular, matrix metalloproteinases (MMPs) represent the major and most investigated protagonists. Owing to their strong involvement in malignant pathologies, MMPs are considered the most promising new biomarkers in cancer diagnosis and prognosis. The interest in studying MMPs in oral cancer biology is also owing to their prominent role in epithelial-to-mesenchymal transition (EMT). EMT is an intricate process involving different complex pathways. EMT-related proteins are attractive diagnostic biomarkers that characterize the activation of biological events that promote cancer's aggressive expansion. Different antioncogenic natural compounds have been investigated to counteract oral carcinogenesis, with the scope of obtaining better clinical results and lower morbidity. In particular, we describe the role of different nutraceuticals used for the regulation of MMP-related invasion and proliferation of oral cancer cells.

Caffeic Acid Phenethyl Ester Induces N-myc Downstream Regulated Gene 1 to Inhibit Cell Proliferation and Invasion of Human Nasopharyngeal Cancer Cells

Caffeic acid phenethyl ester (CAPE), a bioactive component extracted from propolis, is widely studied due to its anti-cancer effect. Nasopharyngeal carcinoma (NPC) is distinct from other head and neck carcinomas and has a high risk of distant metastases. N-myc downstream regulated gene 1 (NDRG1) is demonstrated as a tumor suppressor gene in several cancers. Our result showed that CAPE treatment could repress NPC cell growth, through induction of S phase cell cycle arrest, and invasion. CAPE treatment stimulated NDRG1 expression in NPC cells. NDRG1 knockdown increased NPC cell proliferation and invasion and rendered NPC cells less responsive to CAPE growth-inhibiting effect, indicating CAPE repressed NPC cell growth partly through NDRG1indcution. CAPE treatment increased phosphorylation of ERK, JNK, and p38 in a dose- and time-dependent manner. Pre-treatments by inhibitors of ERK (PD0325901), JNK (SP600125), or p38 (SB201290), respectively, all could partly inhibit the CAPE effect on NDRG1 induction in NPC cells. Further, STAT3 activity was also repressed by CAPE in NPC cells. In summary, CAPE attenuates NPC cell proliferation and invasion by upregulating NDRG1 expression via MAPK pathway and by inhibiting phosphorylation of STAT3. Considering the poor prognosis of NPC patients with metastasis, CAPE could be a promising agent against NPC.

Oncogenic MNK signalling regulates the metastasis suppressor NDRG1

The protein N-myc down-regulated gene 1 (NDRG1) represses tumour metastasis. It is phosphorylated at several sites by serum and glucocorticoid-regulated kinase 1 (SGK1). Here we show that NDRG1 is also regulated by the oncogenic MAP kinase-interacting kinase (MNK) pathway, a target for cancer therapy.Inhibiting MNKs increases the expression of NDRG1 protein and mRNA in breast cancer cells. MNK inhibition also decreases the phosphorylation of NDRG1. Phosphorylation of NDRG1 is reduced in cells lacking MNK1, but not MNK2-knockout cells, indicating that NDRG1 phosphorylation is a specific target for MNK1. However, MNK1 cannot directly phosphorylate NDRG1 in vitro, indicating that additional signalling connections are involved. Taken together, our data indicate that MNK signaling regulates NDRG1 at transcriptional and post-translational levels.We show that SGK1 phosphorylates MNK1 at a conserved site, which represses its activity. NDRG1, SGK1 and the MNKs are implicated in cell migration and metastasis. As expected, knocking-down NDRG1 promoted cell migration. However, whereas MNK inhibition impairs these processes irrespective of NDRG1 levels, SGK inhibition only did so in NDRG1-depleted cells. Thus, MNKs and SGK affect migration/invasion through distinct mechanisms.Our data reveal several novel connections between signalling pathways important for tumour biology.

N-Myc Downstream-Regulated Gene 1 Restricts Hepatitis C Virus Propagation by Regulating Lipid Droplet Biogenesis and Viral Assembly

Host cells harbor various intrinsic mechanisms to restrict viral infections as a first line of antiviral defense. Viruses have evolved various countermeasures against these antiviral mechanisms. Here we show that N-Myc downstream-regulated gene 1 (NDRG1) limits productive hepatitis C virus (HCV) infection by inhibiting viral assembly. Interestingly, HCV infection downregulates NDRG1 protein and mRNA expression. The loss of NDRG1 increases the size and number of lipid droplets, which are the sites of HCV assembly. HCV suppresses NDRG1 expression by upregulating MYC, which directly inhibits the transcription of NDRG1 The upregulation of MYC also leads to the reduced expression of the NDRG1-specific kinase serum/glucocorticoid-regulated kinase 1 (SGK1), resulting in a markedly diminished phosphorylation of NDRG1. The knockdown of MYC during HCV infection rescues NDRG1 expression and phosphorylation, suggesting that MYC regulates NDRG1 at both the transcriptional and posttranslational levels. Overall, our results suggest that NDRG1 restricts HCV assembly by limiting lipid droplet formation. HCV counteracts this intrinsic antiviral mechanism by downregulating NDRG1 via a MYC-dependent mechanism.IMPORTANCE Hepatitis C virus (HCV) is an enveloped single-stranded RNA virus that targets hepatocytes in the liver. HCV is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, and estimates suggest a global prevalence of 2.35%. Up to 80% of acutely infected individuals will develop chronic infection, and as many as 5% eventually progress to liver cancer. An understanding of the mechanisms behind virus-host interactions and viral carcinogenesis is still lacking. The significance of our research is that it identifies a previously unknown relationship between HCV and a known tumor-associated gene. Furthermore, our data point to a new role for this gene in the liver and in lipid metabolism. Thus, HCV infection serves as a great biological model to advance our knowledge of liver functions and the development of liver cancer.

The hypoxia-responsive lncRNA NDRG-OT1 promotes NDRG1 degradation via ubiquitin-mediated proteolysis in breast cancer cells

Hypoxia can lead to solid tumor aggressiveness by driving multiple signaling pathways. Long non-coding RNAs respond to several extrinsic stimuli, causing changes in cancer cells by participating in multiple steps of gene expression. However, genomic profiling of long non-coding RNAs regulated by oxygen in breast cancer remained unclear. Therefore, the aims of this study were to identify oxygen-responsive long non-coding RNAs in breast cancer cells, and to delineate their regulatory mechanisms. The expression profiling of long non-coding RNAs in breast cancer cells growing under normoxic, hypoxic, and re-oxygenated conditions was examined using next-generation sequencing technology. Four hundred and seventy-two lncRNAs oxygen-responsive lncRNAs were identified. After examining the top three differentially expressed lncRNAs in hypoxia, we selected N-Myc Downstream Regulated Gene 1-Overlapping 1 (NDRG1-OT1) for further study, especially the most responsive isoform, NDRG1-OT1_v4. We overexpressed NDRG1-OT1_v4 under normoxia and performed microarray analysis to identify 108 NDRG1-OT1_v4 regulated genes and their functions. Among these genes, we found that both NDRG1 mRNA expression and NDRG1 protein levels were inhibited by NDRG1-OT1_v4. Finally, we used co-immunoprecipitation to show that NDRG1-OT1_v4 destabilizes NDRG1 by promoting ubiquitin-mediated proteolysis. Our findings reveal a new type of epigenetic regulation of NDRG1 by NDRG1-OT1_v4 in breast cancer cells.

Hemidesmosomal linker proteins regulate cell motility, invasion and tumorigenicity in oral squamous cell carcinoma derived cells

BPAG1e and Plectin are hemidesmosomal linker proteins which anchor intermediate filament proteins to the cell surface through β4 integrin. Recent reports indicate that these proteins play a role in various cellular processes apart from their known anchoring function. However, the available literature is inconsistent. Further, the previous study from our laboratory suggested that Keratin8/18 pair promotes cell motility and tumor progression by deregulating β4 integrin signaling in oral squamous cell carcinoma (OSCC) derived cells. Based on these findings, we hypothesized that linker proteins may have a role in neoplastic progression of OSCC. Downregulation of hemidesmosomal linker proteins in OSCC derived cells resulted in reduced cell migration accompanied by alterations in actin organization. Further, decreased MMP9 activity led to reduced cell invasion in linker proteins knockdown cells. Moreover, loss of these proteins resulted in reduced tumorigenic potential. SWATH analysis demonstrated upregulation of N-Myc downstream regulated gene 1 (NDRG1) in linker proteins downregulated cells as compared to vector control cells. Further, the defects in phenotype upon linker proteins ablation were rescued upon loss of NDRG1 in linker proteins knockdown background. These data together indicate that hemidesmosomal linker proteins regulate cell motility, invasion and tumorigenicity possibly through NDRG1 in OSCC derived cells.

The variant of pri-mir-26a-1 polymorphism is associated with decreased risk of betel quid-related oral premalignant lesions and oral squamous cell carcinoma

OBJECTIVES

This case-control study evaluated the association of the single nucleotide polymorphism rs7372209 (T>C) in pri-mir-26a-1 with the risk and progression of betel quid (BQ)-related oral premalignant lesions (OPLs) and oral squamous cell carcinoma (OSCC).

STUDY DESIGN

In total, 597 BQ chewers were recruited: 196 healthy controls, 241 patients with OPLs, and 160 patients with OSCC. Genotypes were determined using the TaqMan real-time assay.

RESULTS

The C/T + T/T genotypes and T allele in pri-mir-26a-1 were correlated with a decreased risk of BQ-related OPLs (P = .038 and .005, respectively), oral leukoplakia (P = .01 and .001, respectively), and advanced-stage OSCC (P = .021 and .004, respectively). The effects of the C/T + T/T genotypes and T allele on the decreased risk of OPLs were potent in the older age group (both P_interaction < .001), heavy smokers (P_interaction ≤ .003 and .006, respectively) and alcohol drinkers (P_interaction ≤ .004 and .001, respectively). Furthermore, among patients with OSCC, the C/T + T/T genotypes and T allele were associated with a decreased risk of advanced pathologic stage (P = .032) and lymph node involvement (P = .017).

CONCLUSIONS

BQ chewers carrying the T allele or C/T + T/T genotypes in pri-mir-26a-1 may have a decreased risk of oral leukoplakia, OPLs, and advanced-stage OSCC.

N-myc downstream-regulated gene 1 inhibits the proliferation and invasion of hepatocellular carcinoma cells via the regulation of integrin β3

N-myc downstream-regulated gene 1 (NDRG1) is a multifunctional protein associated with carcinogenesis and tumor progression. The function of NDRG1 in hepatocellular carcinoma (HCC) cells remains controversial. The present study investigated the role of NDRG1 in HCC as well as its molecular mechanism using a range of techniques, including western blot analysis, cellular proliferation test, wound healing assay and Transwell assay. In HCC, the levels of NDRG1 expression were highest in the cytoplasm, followed by the membrane, and were lowest in the nucleus. NDRG1 was revealed to inhibit the proliferation and invasion of BEL7402 cells, which facilitated the hypothesis that NDRG1 expression levels may be lower in cell line with a high metastatic potential compared with those in cell lines with a low metastatic potential. However, the present study identified that NDRG1 expression was higher in detached BEL7402 cells and MHCC-97H cells compared with that in attached BEL7402 cells and MHCC-97L cells. Thus, this finding was contrary to what was expected, suggesting that NDRG1 overexpression in the HCC with a high metastatic potential may be the compensatory mechanism. The human HCC BEL7402 cell line demonstrated a significant increase in the capability of motility, invasion and cellular proliferation following NDRG1-short hairpin RNA transfection. Integrin β3 (ITGB3) protein expression was increased in NDRG1-downregulated BEL7402 cells and SMMC7721 cells compared with that in the control cells. The present study suggested that NDRG1 may be a potential anti-tumor target for the treatment of patients with HCC. A potential mechanism for these roles of NDRG1 is by regulating ITGB3 expression; however, this requires additional investigation.

Caffeic acid phenethyl ester upregulates N-myc downstream regulated gene 1 via ERK pathway to inhibit human oral cancer cell growth in vitro and in vivo

SCOPE

Caffeic acid phenethyl ester (CAPE), a bioactive component of propolis, is considered as a new anti-cancer agent. Oral squamous cell carcinoma (OSCC) is the most common oral cancer with unsatisfying survival. N-myc downstream regulated family genes (NDRGs) involve in numerous physiological processes. We investigated the anti-cancer effect of CAPE on OSCC and related mechanisms.

METHODS AND RESULTS

Cell proliferation assay, western blot, gene transfection and knockdown, and reporter assay were applied. We showed that CAPE attenuated OSCC cell proliferation and invasion in vitro, and safely and effectively inhibited OSCC cell growth in a xenograft animal model. CAPE treatment induced NDRG1, but not NDRG2 and NDRG3, expression in OSCC cells as determined by western blot, RT-qPCR, and reporter assay. The 5'-deletion assay demonstrated that CAPE increased NDRG1 promoter activity depending on the region of -128 to +46 of the 5'-flanking of NDRG1 gene. NDRG1 gene knockdown attenuated CAPE anti-growth effect on OSCC cells. CAPE activated mitogen-activated protein kinase (MAPK) signaling pathway. The extracellular signal regulated kinase (ERK) inhibitor (PD0325901) and ERK1 knockdown blocked CAPE-induced NDRG1 expression in OSCC cells.

CONCLUSION

CAPE activated MAPK signaling pathway and increased NDRG1 expression through phosphorylation of ERK1/2 to repress OSCC cells growth.

The Iron Chelator, Dp44mT, Effectively Inhibits Human Oral Squamous Cell Carcinoma Cell Growth in Vitro and in Vivo

Oral squamous cell carcinoma (OSCC) is a common malignancy with a growing worldwide incidence and prevalence. The N-myc downstream regulated gene (NDRG) family of NDRG1, 2, 3, and mammary serine protease inhibitor (Maspin) gene are well-known modulators in the neoplasia process. Current research has considered iron chelators as new anti-cancer agents; however, the anticancer activities of iron chelators and their target genes in OSCC have not been well investigated. We showed that iron chelators (Dp44mT, desferrioxamine (DFO), and deferasirox) all significantly inhibit SAS cell growth. Flow cytometry further indicated that Dp44mT inhibition of SAS cells growth was partly due to induction of G1 cell cycle arrest. Iron chelators enhanced expressions of NDRG1 and NDRG3 while repressing cyclin D1 expression in OSCC cells. The in vivo antitumor effect on OSCC and safety of Dp44mT were further confirmed through a xenograft animal model. The Dp44mT treatment also increased Maspin protein levels in SAS and OECM-1 cells. NDRG3 knockdown enhanced the growth of OECM-1 cells in vitro and in vivo. Our results indicated that NDRG3 is a tumor suppressor gene in OSCC cells, and Dp44mT could be a promising therapeutic agent for OSCC treatment.

NDRG1 overexpression promotes the progression of esophageal squamous cell carcinoma through modulating Wnt signaling pathway

N-myc down-regulated gene 1 (NDRG1) has been shown to regulate tumor growth and metastasis in various malignant tumors and also to be dysregulated in esophageal squamous cell carcinoma (ESCC). Here, we show that NDRG1 overexpression (91.9%, 79/86) in ESCC tumor tissues is associated with poor overall survival of esophageal cancer patients. When placed in stable transfectants of the KYSE 30 ESCC cell line generated by lentiviral transduction with the ectopic overexpression of NDRG1, the expression of transducin-like enhancer of Split 2 (TLE2) was decreased sharply, however β−catenin was increased. Mechanistically, NDRG1 physically associates with TLE2 and β−catenin to affect the Wnt pathway. RNA interference and TLE2 overexpression studies demonstrate that NDRG1 fails to active Wnt pathway compared with isogenic wild-type controls. Strikingly, NDRG1 overexpression induces the epithelial mesenchymal transition (EMT) through activating the Wnt signaling pathway in ESCC cells, decreased the expression of E-cadherin and enhanced the expression of Snail. Our study elucidates a mechanism of NDRG1-regulated Wnt pathway activation and EMT via affecting TLE2 and  β-catenin expression in esophageal cancer cells. This indicates a pro-oncogenic role for NDRG1 in esophageal cancer cells whereby it modulates tumor progression.

IKK inhibitor suppresses epithelial-mesenchymal transition and induces cell death in prostate cancer

IκB kinase (IKK)/nuclear factor κB (NF-κB) pathway activation is a key event in the acquisition of invasive and metastatic capacities in prostate cancer. A potent small-molecule compound, BMS-345541, was identified as a highly selective IKKα and IKKβ inhibitor to inhibit kinase activity. This study explored the effect of IKK inhibitor on epithelial-mesenchymal transition (EMT), apoptosis and metastasis in prostate cancer. Here, we demonstrate the role of IKK inhibitor reducing proliferation and inducing apoptosis in PC-3 cells. Furthermore, BMS345541 inhibited IκBα phosphorylation and nuclear level of NF-κB/p65 in PC-3 cells. We also observed downregulation of the N-cadherin, Snail, Slug and Twist protein in a dose-dependent manner. BMS‑345541 induced upregulation of the epithelial marker E-cadherin and phosphorylated NDRG1 at protein level. Moreover, BMS‑345541 reduced invasion and metastasis of PC-3 cells in vitro. In conclusion, IKK has a key role in both EMT and apoptosis of prostate cancer. IKK inhibitor can reverse EMT and induce cell death in PCa cells. IKK was identified as a potential target structure for future therapeutic intervention in PCa.

Knockdown of NDRG1 promote epithelial-mesenchymal transition of colorectal cancer via NF-κB signaling

BACKGROUND

NDRG1 plays important roles in tumor growth and metastasis of colorectal cancer (CRC). The relation between NDRG1 and metastatic colorectal cancer (mCRC) has not been identified and the mechanism of NDRG1 involving in mCRC needs to be elucidated.

METHODS

Correlations between NDRG1 and clinicopathological characteristics and prognosis of 164 patients with mCRC were evaluated. Sensitivity of NDRG1-knockdown colon cancer cell to irinotecan (CPT-11) was determined by MTT assay. Blocking of NF-κB signaling by p65 siRNA interference was carried out to explore the mechanism of NDRG1 involving in epithelial-mesenchymal transition (EMT)-regulated invasion and metastasis of CRC.

RESULTS

NDRG1 expression was significantly negatively correlated with differentiation (P = 0.008) and lymph node metastasis (P = 0.016) of mCRC. NDRG1 was a favorable prognostic factor of mCRC, although might be responsible for CPT-11 resistance in vitro. Knockdown of NDRG1 promoted EMT of CRC cells via NF-κB signaling. Depletion of NDRG1 increased phosphorylation level of NF-κB. E-cadherin expression was increased and Vimentin expression was reduced in the p65-siRNA treated group, compared with the control group (P < 0.001).

CONCLUSIONS

NDRG1 appears to prevent EMT-induced metastasis by attenuating NF-κB signaling in mCRC. NDRG1 may be an independent prognostic factor for good survival of mCRC. J. Surg. Oncol. 2016;114:520-527. © 2016 Wiley Periodicals, Inc.

Targeting cancer by binding iron: Dissecting cellular signaling pathways

Newer and more potent therapies are urgently needed to effectively treat advanced cancers that have developed resistance and metastasized. One such strategy is to target cancer cell iron metabolism, which is altered compared to normal cells and may facilitate their rapid proliferation. This is supported by studies reporting the anti-neoplastic activities of the clinically available iron chelators, desferrioxamine and deferasirox. More recently, ligands of the di-2-pyridylketone thiosemicarbazone (DpT) class have demonstrated potent and selective anti-proliferative activity across multiple cancer-types in vivo, fueling studies aimed at dissecting their molecular mechanisms of action. In the past five years alone, significant advances have been made in understanding how chelators not only modulate cellular iron metabolism, but also multiple signaling pathways implicated in tumor progression and metastasis. Herein, we discuss recent research on the targeting of iron in cancer cells, with a focus on the novel and potent DpT ligands. Several key studies have revealed that iron chelation can target the AKT, ERK, JNK, p38, STAT3, TGF-β, Wnt and autophagic pathways to subsequently inhibit cellular proliferation, the epithelial-mesenchymal transition (EMT) and metastasis. These developments emphasize that these novel therapies could be utilized clinically to effectively target cancer.

Prostate-derived ets factor represses tumorigenesis and modulates epithelial-to-mesenchymal transition in bladder carcinoma cells

Prostate-derived Ets (E-twenty six) factor (PDEF), an epithelium-specific member of the Ets family of transcription factors, has been shown to play a role in suppressing the development of many epithelium-derived cancers such as prostate and breast cancer. It is not clear, however, whether PDEF is involved in the development or progression of bladder cancer. In a comparison between normal urothelium and bladder tumor tissue, we identified significant decreases of PDEF in the tumor tissue. Further, the immunohistochemistry assays indicated a significantly higher immunostaining of PDEF in low-grade bladder tumors. Additionally, the highly differentiated transitional-cell bladder carcinoma RT-4 cells expressed significantly more PDEF levels than the bladder carcinoma HT1376 and the T24 cells. Ectopic overexpression of PDEF attenuated proliferation, invasion, and tumorigenesis of bladder carcinoma cells in vitro and in vivo. PDEF enhanced the expression levels of mammary serine protease inhibitor (MASPIN), N-myc downstream regulated gene 1 (NDRG1), KAI1, and B-cell translocation gene 2 (BTG2). PDEF modulated epithelial-mesenchymal-transition (EMT) by upregulating E-cadherin expression and downregulating the expression of N-cadherin, SNAIL, SLUG, and vimentin, leading to lower migration and invasion abilities of bladder carcinoma cells. Filamentous actin (F-actin) polarization and remodeling were observed in PDEF-knockdown RT-4 cells. Our results suggest that PDEF gene expression is associated with the extent of bladder neoplasia and PDEF modulated the expressions of EMT-related genes. The induction of BTG2, NDRG1, MASPIN, and KAI1 gene expressions by PDEF may explain the inhibitory functions of PDEF on the proliferation, invasion, and tumorigenesis in bladder carcinoma cells.

Suppression of fructose-bisphosphate aldolase C expression as a predictor of advanced oral squamous cell carcinoma

BACKGROUND

Glycolysis machinery regulates cancer cell behavior. However, the roles of these glycolysis enzymes in oral squamous cell carcinoma (OSCC) progression remain unknown.

METHODS

Fructose-bisphosphate aldolase C (ALDOC) expression in OSCC patients and cell lines was detected using quantitative real-time polymerase chain reaction (PCR). The functions of ALDOC in migration and invasion were determined using gain and loss of function approaches. An orthotopic OSCC animal model was performed to investigate the effects of ALDOC on metastasis and tumorigenesis in vivo.

RESULTS

ALDOC expression is negatively significantly correlated with clinical outcome and cell migration in vitro and in vivo. ALDOC blocks adenosine triphosphate generation and lactate production, and mutation constructs of Arg42 and Lys146 functionally restore ALDOC-inhibited cell migration and invasion.

CONCLUSION

ALDOC functions as an OSCC prognosis marker clinically, and suppresses migration and invasion by its catalytic domain of Arg42 and Lys146. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1075-E1085, 2016.

Growth differentiation factor-15: a p53- and demethylation-upregulating gene represses cell proliferation, invasion, and tumorigenesis in bladder carcinoma cells

Growth differentiation factor-15 (GDF15), a member of the TGF-β superfamily, affects tumor biology of certain cancers, but remains poorly understood in bladder cancer cells. This study determined the expression, regulation, function, and potential downstream target genes of GDF15 in bladder carcinoma cells. The transitional papilloma carcionoma cells (RT4) expressed higher levels of GDF15 as compared with the bladder carcinoma cells (HT1376 and T24). Treatments of recombinant human GDF15 (rhGDF15) reduced the proliferations of HT1376 and T24 cells. Expression of GDF15 was upregulated via DNA demethylation and p53. The cell proliferation, invasion, and tumorigenesis were reduced in ectopic overexpression of GDF15, while enhanced in GDF15 knockdown. The expressions of mammary serine protease inhibitor (MASPIN) and N-myc downstream-regulated family genes (NDRG1, NDRG2, and NDRG3) were upregulated by GDF15 overexpressions and rhGDF15 treatments in bladder carcinoma cells. GDF15 knockdown induced epithelial-mesenchymal transition (EMT) and F-actin polarization in HT1376 cells. Our results suggest that enhanced expressions of MASPIN and N-myc downstream-regulated family genes and the modulation of EMT may account for the inhibitory functions of GDF15 in the cell proliferation, invasion, and tumorigenesis of bladder carcinoma cells. The GDF15 should be considered as a tumor suppressor in human bladder carcinoma cells.

Downregulation of N-myc downstream regulated gene 1 caused by the methylation of CpG islands of NDRG1 promoter promotes proliferation and invasion of prostate cancer cells

Current studies tend to consider N-myc downstream regulated gene 1 (NDRG1) as a tumor suppressor gene, inhibiting cell proliferation and invasion. NDRG1 expression in cancer cells is generally low, but the molecular mechanism is unclear. Aberrant methylation of CpG islands (CGIs) in gene promoter was able to inactivate tumor suppressor genes and activate oncogenes, disordering cell proliferation and apoptosis, playing a promotion role in tumor occurrence and progression. The present study was performed to investigate the effect of epigenetic modification of NDRG1 on prostate cancer (PCa) cells. The protein expression in human specimens was measured by immunohistochemical staining. The expression level of NDRG1 was changed by plasmid vectors in PCa cells. These cells were used to study proliferation and invasiveness. NDRG1 expression in normal prostate cells was higher than that in PCa cells. Downregulation of NDRG1 expression enhanced cell proliferation and invasiveness. In contrast, its upregulation could reduce cell proliferation and invasiveness. In PCa cells, the methylation rate of CGIs in the promoter region of NDRG1 was higher than that in normal prostate cells. 5-Aza-CdR, a methylation inhibitor, was able to effectively reverse the aberrant methylation of NDRG1, enhancing its expression, inhibiting cell growth. NDRG1 can inhibit the cell proliferation and invasion of PCa, but its expression level is low. The aberrant methylation of NDRG1 promoter is an important mechanism for gene silencing, playing an important role in tumor occurrence and progression. Therefore, reversing the aberrant methylation of NDRG1 may be used for PCa treatment.

NDRG1 attenuates epithelial-mesenchymal transition of nasopharyngeal cancer cells via blocking Smad2 signaling

N-myc downstream-regulated gene 1 (NDRG1) has been implicated in tumorigenesis and metastasis in different cancers. However, its role in nasopharyngeal carcinoma remains unknown. We found that NDRG1 expression level was high in nasopharyngeal cancer 5-8F cells but low in 5-8F-LN cells with lymphatic metastasis potential. Knockdown of NDRG1 by shRNA promoted 5-8F cell proliferation, migration, and invasion in vitro and its tumorigenesis in vivo. Moreover, NDRG1 deficiency induced an epithelial-mesenchymal transition (EMT) of 5-8F cells as shown by an attenuation of E-cadherin and an induction of N-cadherin and vimentin expression. NDRG1 knockdown also enhanced Smad2 expression and phosphorylation. Smad2 signaling was attenuated in 5-8F cells but was significantly activated in 5-8F-LN cells. Knockdown of Smad2 restored E-cadherin but attenuated N-cadherin expression in NDRG1-deficient 5-8F cells, suggesting a reduction of EMT. Consistently, blockade of Smad2 in 5-8F-LN cells increased E-cadherin while diminishing N-cadherin and vimentin expression. These data indicate that Smad2 mediates the NDRG1 deficiency-induced EMT of 5-8F cells. In tumors derived from NDRG1-deficient 5-8F cells, E-cadherin expression was inhibited while vimentin and Smad2 were increased in a large number of cancer cells. Most importantly, NDRG1 expression was attenuated in human nasopharyngeal carcinoma tissues, resulted in a lower survival rate in patients. The NDRG1 was further decreased in the detached nasopharyngeal cancer cells, which was associated with a further reduced survival rate in patients with lymphatic metastasis. Taken together, these results demonstrated that NDRG1 prevents nasopharyngeal tumorigenesis and metastasis via inhibiting Smad2-mediated EMT of nasopharyngeal cells.

WNT-1 inducible signaling pathway protein-1 enhances growth and tumorigenesis in human breast cancer

WNT1 inducible signaling pathway protein 1 (WISP1) plays a key role in many cellular functions in a highly tissue-specific manner; however the role of WISP1 in breast cancer is still poorly understood. Here, we demonstrate that WISP1 acts as an oncogene in human breast cancer. We demonstrated that human breast cancer tissues had higher WISP1 mRNA expression than normal breast tissues and that treatment of recombinant WISP1 enhanced breast cancer cell proliferation. Further, ectopic expression of WISP1 increased the growth of breast cancer cells in vitro and in vivo. WISP1 transfection also induced epithelial-mesenchymal-transition (EMT) in MCF-7 cells, leading to higher migration and invasion. During this EMT-inducing process, E-cadherin was repressed and N-cadherin, snail, and β-catenin were upregulated. Filamentous actin (F-actin) remodeling and polarization were also observed after WISP1 transfection into MCF-7 cells. Moreover, forced overexpression of WISP1 blocked the expression of NDRG1, a breast cancer tumor suppressor gene. Our study provides novel evidence that WISP1-modulated NDRG1 gene expression is dependent on a DNA fragment (-128 to +46) located within the human NDRG1 promoter. Thus, we concluded that WISP1 is a human breast cancer oncogene and is a potential therapeutic target.